The use of various cutters for cutting piping and tubing is common place. Typically, piping or tubing is manufactured and delivered to end users in predetermined lengths that exceed the lengths required by the end users for specific jobs or tasks. As a result, various cutters are needed to cut the piping or tubing to specifically desirable lengths, either before or after installation.
Dual containment tubing systems generally consist of an outer tubing and an inner tubing. The tubing is made of plastic material and, in the field of semiconductor processing in particular, the tubing is often made of special plastics such as PFA, FEP, Olefin (such as HDPE or PP), or other fluorinated hydrocarbons that have suitable chemical resistance. These resistant resins or plastics are required in the processing of semi-conductor wafers into integrated circuits since highly corrosive, ultra-pure fluids, such as hydrochloric, sulfuric and hydrofluoric acid, are utilized, often in extreme temperature ranges.
In such dual containment tubing systems such as these, it is often necessary to merely cut the outer tubing. However, in doing so, it is essential that the inner tubing, or tubings, not be damaged, or themselves cut. This is a potential problem since it is not uncommon for the inner tubing to shift or rest against, or extremely close to, the inner surface of the outer tubing.
The vast majority of conventional cutters are wrench-like or plier-like devices for engaging piping or tubing for rotational movement around the outer diameter of the tubing. Generally, these devices implement discs or rollers to facilitate the rotational movement, with at least one of the discs having a bladed edge for cutting. The key to such devices is to keep the cutting edges of the discs in biased engaged against the piping or tubing such that necessary blade force is continuously applied for the entire rotational period. This biased engagement is typically achieved by human force upon two generally paralled handle portions, such as those used in other tools like wrenches and pliers, or with other force actuating means. These devices comprise relatively complex springs, pins, racheting means, gears, and other systems and components needed to promote cutting force and the circumferential adjustability of the rollers and disc blades around the piping or tubing of various outer diameters. U.S. Pat. Nos. 4,305,205 and 5,206,996 disclose such devices.
U.S. Pat. Nos. 4,831,732 and 5,285,576 disclose a variation on the disc and roller designs. Each has rollers and disc blades to enable rotational cutting around piping. However, unlike the previously discussed tools, these cutters do not actuate force upon the piping with adjustable wrench-like or plier-like techniques. Instead, these cutters rely primarily on spring-biased engagement. These cutters are generally C-shaped or cylindrical for receiving piping such that the rollers provide a measurable containment of the piping within the cutter at tangential points of contact. The piping does not engage in substantial contact with the rollers or any other surface of the cutters as a result of these limited tangential contacts.
There have been some attempts at creating cutters that utilize a straight cutting blade rather than traditional disc blades. These straight blade cutters are particularly useful in cutting plastic tubing or pipes. The relatively malleable and soft plastic material makes it possible to cut through the tubing with fewer rotational passes over the surface of the tubing. U.S. Pat. Nos. 4,734,982 and 4,739,554 are two examples of such tubing cutters. One embodiment of the '554 patent utilizes a series of ledges opposite the cutting blade such that tangential contacts are made at the blade and on the applicable ledge. These ledges are variably distanced from the blade in an attempt to permit receipt of tubing of various diameters. However, like many conventional cutters, it merely receives the tubing at tangential points of contact, thus lacking the ability to truly grasp onto the tubing to better facilitate precise and even cutting. The '982 patent suffers from similar drawbacks.
While the cutter disclosed in the '982 patent is cylindrical it also fails to adequately grasp or snap onto the plastic tubing. Rather than tightly engaging the tubing, the cutter blade is adjustably moved in and out of the receiving aperture of the tool to engage the tubing so that tubing of various potential diameters can be received by the cutter. However, this attempt at increasing the ability to cut various-sized tubing leaves the cutter incapable of properly grasping the tubing such that precise and even cutting is facilitated. The adjustability of the blade positioning merely results in extended tangential contacts with any tubing that is not substantially identical in diameter to that of the apertures.
None of these conventional techniques and devices disclose a cutter ideal for cutting dual containment tubing systems. Consequently, there is a need for a C-shaped tubing cutter designed to “snap” onto and grasp the tubing such that rotation of the cutter around the outer surface of the tubing causes the cutter's fixed blade to cut the tubing to a depth short of complete penetration through the wall of the tubing. In addition, this C-shaped cutter should circumferentially engage the tubing along a significant portion of the outer circumference of the tubing to facilitate secure and precise cutting action. Further, this desired tubing cutter should be of relatively simplistic design, designed for securement and use within small spaces, and made of a relatively low-friction, contaminant-resistant plastic.